Pipe expanding punch

ABSTRACT

Disclosed is a pipe expanding punch for a drill, which is configured to expand a pipe by hitting the pipe by an anchor drill or a rechargeable drill. The pipe expanding punch includes: an expanding mandrel provided with at least one portion (hereinafter referred to as “an expanding part”) having an outer diameter larger than an inner diameter of a pipe to be expanded; and a holder formed integrally with the expanding mandrel and fixedly coupled to a drill such that the pipe is expanded using the drill, wherein the outer diameter of an introduction part of an end portion of the expanding mandrel is smaller than the inner diameter of the pipe, a first tapered step is provided between the introduction part and the expanding part, and at least one polished flat surface is formed by polishing the first tapered step.

TECHNICAL FIELD

The present invention relates to a pipe expanding punch, and more particularly, to a pipe expanding punch used with a drill, which is configured to expand a pipe by being rotated or hitting the pipe by an anchor drill or a rechargeable drill.

BACKGROUND ART

In general, household appliances such as refrigerators, air conditioners, water purifiers, etc. are provided with refrigeration cycles for cooling.

In a typical refrigeration cycle of household appliances, a compressor and a condenser are connected to a connection tube, the condenser and an evaporator are connected to a capillary tube through a refrigerant supply tube, and the evaporator and the compressor are connected to a suction pipe.

Such a refrigeration cycle includes a compressor for compressing gas refrigerant into a high-temperature and high-pressure state, a condenser for condensing the high-temperature and high-pressure gas refrigerant discharged from the compressor, and an evaporator in which low-temperature and low-pressure liquid refrigerant that has passed through the capillary tube through the condenser absorbs latent heat of vaporization, thereby performing cooling.

The refrigerant circulates in the refrigeration cycle. The refrigerant from the evaporator passes through the condenser and the capillary tube and returns to the evaporator by driving of the compressor.

The connection tube, the refrigerant supply tube, the capillary tube, the suction pipe and the like provided in the refrigeration cycle are made of a copper pipe, etc. In order to facilitate connection, a front end of one pipe is expanded to a predetermined diameter, another pipe is inserted into the expanded pipe, and then welding is performed to connect the pipes.

In order to expand the pipe, it is necessary to simultaneously expand an inner diameter and an outer diameter of the pipe by inserting a rigid expanding mandrel having an outer diameter larger than the inner diameter of the pipe into the inner diameter of the pipe to be expanded, wherein the expanding mandrel is used in connection with a round bar called a rod bar.

When a pipe is expanded in the field using the expanding mandrel in the related art, the expanding mandrel whose outer diameter is formed stepwise according to the size of the pipe is inserted into the pipe. Then, in a state in which the pipe is fixed, the rod bar, which is combined with the expanding mandrel, is hit with a hammer from behind and thereby pipe expansion work is carried out.

However, the expanding mandrel in the related art has a circular cross section, which incurs a large load during the pipe expansion work, generating a large amount of heat and thus the pipe may not be expanded efficiently.

In addition, since hitting is manually performed by hand-holding the hammer, a user's movement may be restricted because of carrying a heavy hammer and thus may lack sufficient power for the pipe expansion work.

Disclosure Technical Problem

Accordingly, the present invention has been made keeping in mind the above problems occurring in the related art, and an object of the present invention is to provide a pipe expanding punch which is configured such that an expanding mandrel having an elliptical cross section and a holder allowing pipe expansion work to be performed using a drill are formed integrally with each other, whereby less heat is generated and thus a pipe is expanded efficiently during the pipe expansion work, and which can expand the pipe using a drill, thereby requiring low power and requiring no hammer to be carried, and thus being easy to use.

Technical Solution

In order to accomplish the above object, the present invention provides a pipe expanding punch, including: an expanding mandrel provided with at least one portion (hereinafter referred to as “an expanding part”) having an outer diameter larger than an inner diameter of a pipe to be expanded; and

a holder formed integrally with the expanding mandrel and fixedly coupled to a drill such that the pipe is expanded using the drill,

wherein the outer diameter of an introduction part of an end portion of the expanding mandrel is smaller than the inner diameter of the pipe, a first tapered step is provided between the introduction part and the expanding part, and

at least one polished flat surface is formed by polishing the first tapered step.

A cross section of the expanding part may have an elliptical shape having unequal radii.

Further, when at least two expanding parts are provided, a second tapered step may be provided between the two expanding parts, and at least one polished flat surface may be formed by polishing the second tapered step.

The expanding mandrel may be provided on an outer circumferential surface thereof with a left-hand screw part or a right-hand screw part formed by alternately forming thread roots and thread crests in a left-hand screw direction or a right-hand screw direction.

Further, the thread crests may have an outwardly rounded shape.

Further, the thread crests may be larger than the thread roots in width.

Further, in a case where the introduction part is directed to left and the right-hand screw part is provided, the thread roots may be formed along above diagonal lines passing through the first and second steps of a narrow side surface, which has a relatively large radius, from upper left to lower right, and in a case where the introduction part is directed to left and the left-hand screw part is provided, the thread roots may be formed along below diagonal lines passing through the first and second steps of the narrow side surface, which has the relatively large radius, from upper right to lower left.

Further, in a case where the expanding mandrel is divided quarterly horizontally and vertically, with respect to a vertical line, a portion of a front upper quadrant of a narrow side surface having a relatively large radius may be cut by passing along a plurality of expanding parts and a plurality of first and second steps in accordance with a rotational direction of the expanding mandrel.

Further, the polished flat surfaces may be provided respectively on the first and second tapered steps of a narrow side surface having a relatively large radius.

Further, the holder may have a shape being capable of being coupled to a socket of a rechargeable drill and may be shaped in a hexagonal bar, or

the holder may have a shape being capable of being coupled to a socket of an anchor drill and may be shaped in a round bar, the holder being provided in an outer circumferential surface thereof with fitting grooves formed diagonally oppositely, and in the outer circumferential surface thereof with fixing grooves formed diagonally oppositely between the fitting grooves.

Advantageous Effects

According to the above-described technical solution, in the present invention, the expanding mandrel having an elliptical cross section and the holder allowing pipe expansion work to be performed using a drill are formed integrally with each other, whereby less heat is generated and thus a pipe is expanded efficiently during the pipe expansion work, and which can expand the pipe using a drill, thereby requiring low power and requiring no hammer to be carried, and thus being easy to use.

DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view showing a pipe expanding punch according to a first embodiment of the present invention.

FIG. 2 is an exemplary view showing an outer diameter of an expanding mandrel shown in FIG. 1.

FIG. 3 is a perspective view showing a pipe expanding punch according to a second embodiment of the present invention.

FIGS. 4 and 5 are exemplary views showing an outer diameter of an expanding mandrel shown in FIG. 3.

FIG. 6 is a view showing pipe expanding work using the pipe expanding punch shown in FIG. 3.

FIGS. 7 and 8 are front views showing an expanding mandrel according to a third embodiment of the present invention.

FIGS. 9 and 10 are front views showing an expanding mandrel according to a fourth embodiment of the present invention.

FIGS. 11 and 12 are front views showing an expanding mandrel according to a fifth embodiment of the present invention.

FIG. 13 is a side view showing the expanding mandrel according to the present invention.

MODE FOR INVENTION

Hereinafter, a configuration and operation of exemplary embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a perspective view showing a pipe expanding punch according to a first embodiment of the present invention, and FIG. 2 is an exemplary view showing an outer diameter of an expanding mandrel shown in FIG. 1, wherein the pipe expanding punch is used with a rechargeable drill.

As shown in FIG. 1, the pipe expanding punch 10 according to the first embodiment of the present invention is configured such that the expanding mandrel 20 and a holder 30 are made of a rigid material and are provided integrally with each other.

The expanding mandrel 20 is provided with an expanding part 22 having an outer diameter larger than an inner diameter of a pipe to be expanded, and an introduction part 24 provided at an end portion of the expanding mandrel and having an outer diameter smaller than the inner diameter of the pipe such that insertion into the pipe is facilitated.

Further, a tapered step 26 is provided between the expanding part 22 and the introduction part 24 such that pipe expansion is facilitated.

Herein, at least one polished flat surface 120 is formed by polishing the tapered step 26.

Meanwhile, a cross section of the expanding part 22 has an elliptical shape that is a round shape having unequal radii.

For example, as shown in FIG. 2, in a case where the outer diameter of the expanding part 22 is 16.7 mm, a radius R thereof is not constant at 8.85 mm, but varies to 8.35 mm, 8.85 mm, and 9.6 mm in each point, resulting in a round shape having unequal radii.

The holder 30 is used by being combined with a rechargeable drill and has a shape capable of being coupled to a socket of the rechargeable drill, the holder being shaped in a hexagonal bar.

The expanding mandrel 20 and the holder 30 are integrated into a single body, and a stopper 40 having an outer diameter larger than the outer diameter of the expanding part 22 is provided between the expanding mandrel 20 and the holder 30 such that undesirable expansion of the pipe is limited.

On the other hand, the rechargeable drill is generally used for drilling a hole by rotation of a bit. In the present invention, an impact driver is used to expand the pipe by rotating or hitting the pipe expanding punch 10.

FIG. 3 is a perspective view showing a pipe expanding punch according to a second embodiment of the present invention, and FIGS. 4 and 5 are views showing an outer diameter of an expanding mandrel shown in FIG. 3, wherein the pipe expanding punch is used with an anchor drill.

As shown in FIG. 3, a pipe expanding punch 50 according to the second embodiment of the present invention is configured such that an expanding mandrel 60 and a holder 70 are made of a rigid material and are provided integrally with each other.

The expanding mandrel 60 is provided with two expanding parts (first and second expanding parts 61 and 62) having outer diameters larger, respectively, than inner diameters of pipes to be expanded such that two pipes having different inner diameters are expandable using one pipe expanding punch 50. Herein, a tapered step 64 is provided between the first and second expanding parts 61 and 62 such that pipe expansion is facilitated.

In addition, in order to facilitate insertion to the pipes, an introduction part 63 provided at an end portion of the expanding mandrel 60 is configured that an outer diameter thereof is smaller than the inner diameters of the pipes. Herein, a tapered step 65 is provided between the second expanding part 62 and the introduction part 63 such that pipe expansion is facilitated.

Herein, cross sections of the first and second expanding parts 61 and 62 have an elliptical shape that is round shape having unequal radii.

For example, as shown in FIG. 4, in a case where the outer diameter of the second expanding part 62 is 7 mm, a radius R thereof is not constant at 3.5 mm, but varies to 3.43 mm, 2.88 mm, and 4.8 mm in each point, resulting in a round shape having unequal radii.

In addition, as shown in FIG. 5, in a case where the outer diameter of the first expanding part 61 is 10.5 mm, a radius R thereof is not constant at 5.25 mm, but varies to 5.18 mm, 4.63 mm, 6.55 mm, and 5.25 mm in each point, resulting in a round shape having unequal radii.

The holder 70 is used by being fixedly combined with an anchor drill and has a shape capable of being coupled to a socket of the anchor drill. The holder 70 is shaped in a round bar and is provided in an outer circumferential surface thereof with fitting grooves 72 formed diagonally oppositely, and in the outer circumferential surface thereof with fixing grooves 74 formed diagonally oppositely between the fitting grooves 72.

Herein, the fitting grooves 72 are formed by extending from an end portion to a predetermined position of the round bar, and the fixing grooves 74 are formed between the fitting grooves 72 on an outer circumferential surface of the round bar.

The expanding mandrel 60 and the holder 70 are integrated into a single body, and a stopper 80 having the largest diameter of the expanding mandrel, that is, having an outer diameter larger than the outer diameter of the first expanding part 61 is provided between the expanding mandrel 60 and the holder 70 such that undesirable expansion of the pipes is limited.

On the other hand, the anchor drill is used to drill a hole by rotation or hitting, thereby expanding the pipes.

FIG. 6 is a view showing pipe expanding work using the pipe expanding punch shown in FIG. 3.

As shown in FIG. 6, the holder 70 of the pipe expanding punch 50 is fixedly combined with an anchor drill

B while a pipe P is fixed so as not to move, and the introduction part 63 of the end portion of the expanding mandrel 60 is allowed to approach an inner diameter the pipe.

Then, one of the expanding parts 61 and 62 of the expanding mandrel 60, which has an outer diameter larger than the inner diameter of the pipe P, is inserted into the pipe P by the pipe expanding punch 50 due to a heading operation of the anchor drill B, whereby the inner and outer diameters of the pipe P are simultaneously expanded.

FIGS. 7 and 8 are front views showing an expanding mandrel according to a third embodiment of the present invention.

As shown in FIG. 7, an expanding mandrel 100 having an elliptical shape that is a round shape having unequal radii is provided with two expanding parts (first and second expanding parts 101 and 102) having outer diameters larger, respectively, than inner diameters of pipes to be expanded such that two pipes having different inner diameters are expandable using one pipe expanding punch. Herein, a tapered step 104 is provided between the first and second expanding parts 101 and 102 such that pipe expansion is facilitated.

Furthermore, in order to facilitate insertion to the pipes, an introduction part 103 provided at an end portion of the expanding mandrel 100 is configured that an outer diameter thereof is smaller than the inner diameters of the pipes. Herein, a tapered step 105 is provided between the second expanding part 102 and the introduction part 103 such that pipe expansion is facilitated.

The expanding mandrel 100 having the above configuration is provided on an outer circumferential surface thereof with a right-hand screw part 110 formed by alternately forming thread roots 111 and thread crests 112 in a right-hand screw direction, wherein the thread crests 112 are outwardly rounded such that generation of sludge (foreign matter) is prevented during pipe expansion.

In addition, at least one polished flat surface 120 having a substantially isosceles trapezoidal shape is formed by polishing a narrow side surface of each of the tapered step portions 104 and 105, which has a relatively large radius, such that pipe expansion is facilitated.

The right-hand screw part 110 serves to reduce friction by reducing a contact area with the pipe, thereby minimizing frictional heat generated inside the pipe while facilitating pipe expansion, reducing strain rates of the pipe, and reducing generation of foreign matter during pipe expansion by reducing breakage of the pipe due to the rounded thread crests 112.

As shown in FIG. 8, an expanding mandrel 100 having an elliptical shape that is a round shape having unequal radii is provided with two expanding parts (first and second expanding parts 101 and 102) having outer diameters larger, respectively, than inner diameters of pipes to be expanded such that two pipes having different inner diameters are expandable using one pipe expanding punch. Herein, a tapered step 104 is provided between the first and second expanding parts 101 and 102 such that pipe expansion is facilitated.

Furthermore, in order to facilitate insertion to the pipes, an introduction part 103 provided at an end portion of the expanding mandrel 100 is configured that an outer diameter thereof is smaller than the inner diameters of the pipes. Herein, a tapered step 105 is provided between the second expanding part 102 and the introduction part 103 such that pipe expansion is facilitated.

The expanding mandrel 100 having the above configuration is provided on an outer circumferential surface thereof with a left-hand screw part 130 formed by alternately forming thread roots 131 and thread crests 132 in a left-hand screw direction, wherein the thread crests 132 are outwardly rounded such that generation of sludge (foreign matter) is prevented during pipe expansion.

In addition, at least one polished flat surface 120 having a substantially isosceles trapezoidal shape is formed by polishing a narrow side surface of each of the tapered step portions 104 and 105, which has a relatively large radius, such that pipe expansion is facilitated.

The left-hand screw part 130 serves to reduce friction by reducing a contact area with the pipe, thereby minimizing frictional heat generated inside the pipe while facilitating pipe expansion, reducing strain rates of the pipe, and reducing generation of foreign matters during pipe expansion by reducing breakage of the pipe due to the rounded thread crests 132.

The right-hand screw part 110 is advantageous in expanding a pipe having a small inner diameter and thin walls, whereas the left-hand screw part 130 is advantageous in expanding a pipe having a large inner diameter.

FIGS. 9 and 10 are front views showing an expanding mandrel according to a fourth embodiment of the present invention, wherein FIG. 9 shows a wide side surface of an elliptical expanding mandrel, which has a relatively small radius, and FIG. 10 shows a narrow side surface of the elliptical expanding mandrel, which has a relatively large radius.

In FIG. 7, the right-hand screw part 110 is configured such that the thread roots 111 are larger than the thread crests 112 in width. However, in FIGS. 9 and 10 showing the fourth embodiment, the right-hand screw part 110 is configured such that the thread roots 111 are smaller than the thread crests 112 in width.

Furthermore, in FIG. 9, tapered steps 104 and 105 on a wide side surface having a relatively small radius are polished to respectively form a round flat surface (indicated by a dotted line) such that pipe expansion is facilitated, thereby forming at least one polished flat surface 120 having a substantially isosceles trapezoidal shape.

In this case, the steps 104 and 105 are firstly machined to form the round flat surfaces such that the polished flat surfaces 120 are formed before the thread roots 111 are machined, and then opposed parts of the polished flat surfaces 120 are chamfered based on the thread roots 111.

Thus, generation of sludge can be prevented and heat generation can be reduced.

In addition, as shown in FIG. 10, positions of the thread roots 111 formed on the narrow side surface having a relatively large radius greatly influence ease of pipe expansion. Thus, in a case where an introduction part 103 is directed to left, the thread roots 111 are formed along above diagonal lines a-b and c-d passing through the steps 104 and 105 from upper left to lower right (right of the lines a-b and c-d in the drawing), such that comb-shaped portions provide motive power for facilitating pipe expansion.

FIGS. 11 and 12 are front views showing an expanding mandrel according to a fifth embodiment of the present invention, wherein FIG. 11 shows a wide side surface of an elliptical expanding mandrel, which has a relatively small radius, and FIG. 12 shows a narrow side surface of the elliptical expanding mandrel, which has a relatively large radius.

In FIG. 8, the left-hand screw part 130 is configured such that the thread roots 131 are larger than the thread crests 132 in width. However, in FIGS. 11 and 12 showing the fifth embodiment, the left-hand screw part 130 is configured such that the thread roots 131 are smaller than the thread crests 132 in width.

Furthermore, in FIG. 11, tapered steps 104 and 105 on a wide side surface having a relatively small radius are polished to respectively form a round flat surface (indicated by a dotted line) such that pipe expansion is facilitated, thereby forming at least one polished flat surface 120 having a substantially isosceles trapezoidal shape.

In this case, the steps 104 and 105 are firstly machined to form the round flat surfaces such that the polished flat surfaces 120 are formed before the thread roots 111 are machined, and then opposed parts of the polished flat surfaces 120 are chamfered based on the thread roots 111.

Thus, generation of sludge can be prevented and heat generation can be reduced.

In addition, as shown in FIG. 12, positions of the thread roots 131 formed on the narrow side surface having a relatively large radius greatly influence ease of pipe expansion. Thus, in a case where an introduction part 103 is directed to left, the thread roots 131 are formed along below diagonal lines a-b and c-d passing through the steps 104 and 105 from upper right to lower left (left of the lines a-b and c-d in the drawing), such that comb-shaped portions provide motive power for facilitating pipe expansion.

FIG. 13 is a side view showing the expanding mandrel according to the present invention.

In the expanding mandrel 100 having an elliptical shape that is a round shape having unequal radii, when the expanding mandrel is divided quarterly horizontally and vertically, with respect to a vertical line, a portion of a front upper quadrant of a narrow side surface having a relatively large radius is cut in accordance with a rotational direction.

In other words, as shown in FIG. 13, when the expanding mandrel 100 is rotated in a counterclockwise direction, a portion of a fourth quadrant is cut flat, which corresponds to a direction of about 10 to 12 o'clock. On the other hand, when the expanding mandrel 100 is rotated in a clockwise direction, a portion of a first quadrant is cut flat, which corresponds to a direction of about 12 to 2 o'clock.

In FIGS. 9 and 10, and FIGS. 11 and 12, this cutting is performed with respect to the first and second expanding parts 101 and 102 and the tapered steps 104 and 105 except for the introduction part 103.

Thus, even with a small power and a small number of revolutions of the drill, it is possible to facilitate pipe expansion by motive power generated by rotation and to reduce heat generation. 

1. A pipe expanding punch, comprising: an expanding mandrel provided with at least one portion (hereinafter referred to as “an expanding part”) having an outer diameter larger than an inner diameter of a pipe to be expanded; and a holder formed integrally with the expanding mandrel and fixedly coupled to a drill such that the pipe is expanded using the drill, wherein the outer diameter of an introduction part of an end portion of the expanding mandrel is smaller than the inner diameter of the pipe, a first tapered step is provided between the introduction part and the expanding part, and at least one polished flat surface is formed by polishing the first tapered step.
 2. The pipe expanding punch of claim 1, wherein a cross section of the expanding part has an elliptical shape having unequal radii.
 3. The pipe expanding punch of claim 1, wherein when at least two expanding parts are provided, a second tapered step is provided between the two expanding parts, and at least one polished flat surface is formed by polishing the second tapered step.
 4. The pipe expanding punch of claim 3, wherein the expanding mandrel is provided on an outer circumferential surface thereof with a left-hand screw part or a right-hand screw part formed by alternately forming thread roots and thread crests in a left-hand screw direction or a right-hand screw direction.
 5. The pipe expanding punch of claim 4, wherein the thread crests have an outwardly rounded shape.
 6. The pipe expanding punch of claim 4, wherein the thread crests are larger than the thread roots in width.
 7. The pipe expanding punch of claim 4, wherein in a case where the introduction part is directed to left and the right-hand screw part is provided, the thread roots are formed along above diagonal lines passing through the first and second steps of a narrow side surface, which has a relatively large radius, from upper left to lower right, and in a case where the introduction part is directed to left and the left-hand screw part is provided, the thread roots are formed along below diagonal lines passing through the first and second steps of the narrow side surface, which has the relatively large radius, from upper right to lower left.
 8. The pipe expanding punch of claim 3, wherein in a case where the expanding mandrel is divided quarterly horizontally and vertically, with respect to a vertical line, a portion of a front upper quadrant of a narrow side surface having a relatively large radius is cut flat by passing along a plurality of expanding parts and a plurality of first and second steps in accordance with a rotational direction of the expanding mandrel.
 9. The pipe expanding punch of claim 3, wherein the polished flat surfaces are provided respectively on the first and second tapered steps of a narrow side surface having a relatively large radius.
 10. The pipe expanding punch of claim 1, wherein the holder has a shape being capable of being coupled to a socket of a rechargeable drill and is shaped in a hexagonal bar, or the holder has a shape being capable of being coupled to a socket of an anchor drill and is shaped in a round bar, the holder being provided in an outer circumferential surface thereof with fitting grooves formed diagonally oppositely, and in the outer circumferential surface thereof with fixing grooves formed diagonally oppositely between the fitting grooves. 